摘要
曲江断裂位于川滇菱形块体的东南端,沿该断裂地震活动强烈,是1970年M_s7.7通海地震的发震断裂。基于遥感影像解译、野外地质和构造地貌观测结果、断裂几何学及运动学解析,总结认为曲江断裂第四纪以来以右旋走滑为主且具有倾滑运动分量,沿断裂走向运动学存在差异。NW段以右旋走滑为主,局部有明显正断分量;SE段为右旋走滑兼NE盘向SW盘逆冲。曲江断裂在全新世活动强烈,沿走向错断地貌广泛发育,累积水平位错量3.7~830m。通过对错断地质体、地貌单元的断距进行测量,并对其进行14C或光释光定年,得到断裂晚第四纪平均滑动速率为2.3~4.0mm/a。断裂活动速率的变化与运动学分段有很好的响应:NW段断裂以右旋走滑为主,滑动速率〉3.0mm/a,存在0.6~0.8mm/a的构造抬升;由于受到小江断裂的影响,断裂sE段逆冲分量增加,滑动速率相应降低(〈3.0mm/a),存在1.1mm/a的构造抬升,表明断裂NW段和SE段存在差异抬升。
The Qujiang Fault is one of the most seismically active faults in western Yunnan,China and is considered to be the seismogenic fault of the 1970 Ms7.7 Tonghai earthquake.The Qujiang Fault is located at the southeastern tip of the Sichuan-Yunnan block.In this study,we examine the geometry,kinematics,and geomorphology of this fault through field observations and satellite images.The fault is characterized by dextral strike-slip movements with dip-slip components and can be divided into northwest and southeast segments according to different kinematics.The northwest segment shows right-lateral strike-slip with normal components,whereas it is characterized by dextral movements with the northeast wall thrusting over the opposite in the southeast segment.The offset landforms are well developed along the strike of the fault with displacements ranging from 3.7m to 830m.The Late Quaternary right-lateral slip rate was determined to be 2.3-4.0mm/a through dating and measuring on the offset features.The variation of the slip and uplift rates along the fault strike corresponds well to the fault kinematics segmentation:the slip rate on the northwest segment is above 3mm/a with an uplift rate of 0.6~0.8mm/a;however,influenced by the Xiaojiang Fault,the southeast segment shows apparent thrust components.The slip rate decreases to below 3.0mm/a with an uplift rate of 1.1 mm/a,indicating different uplift between the northwest and southeast segments.
作者
王洋
张波
侯建军
艾晟
WANG Yang;ZHANG Bo;HOU Jian-jun;Ai Sheng(The Key Laboratory of Orogenic Belts and Crustal Evolution,School of Earth and Space Sciences,Peking University,Beijing 100871,China)
出处
《地震地质》
EI
CSCD
北大核心
2015年第4期1177-1192,共16页
Seismology and Geology
基金
中国地震局灾害防御司项目"中国地震活动断层探察:南北地震带南段"(201108001)
国家自然科学基金(41272217)共同资助
关键词
曲江断裂
晚第四纪
右旋走滑
错断地貌
滑动速率
Qujiang Fault
late Quaternary
dextral strike-slip
offset landforms
slip rate
